The race to represent the heart of Fairfax County has money, energy and an unusual pledge by the two main candidates, Republican John Mason and Democrat David Bulova: In a campaign season marked by furious attacks, the rivals for the 37th District House of Delegates seat have sworn off negative campaigning.

That doesn't mean that Mason, a longtime Fairfax City mayor, and Bulova, an environmental expert and the son of Fairfax Supervisor Sharon S. Bulova (D-Braddock), have dropped their competitive guard.

They've been vigorously outlining what they say are their differences and have offered the occasional dig. But each says his opponent has honored the pledge to shun personal attacks.

Their approach is a reflection of their political personalities and of the district they hope to represent. The existence of an open seat and the absence of a consistent party inclination in the district have left the seat up for grabs. Legislators around the state are expected to be easily reelected in districts carefully drawn to protect them.

Voters in the 37th District, which covers central Fairfax, including the city, for years supported Republican candidates in state and federal elections. But they elected Democrat J. Chapman Petersen as delegate in 2001 and supported Sen. John F. Kerry (D-Mass.) for president in 2004.

Mason and Bulova have sought to address residents' anxiety over snarled traffic. Both say they would work to get back more of the money Fairfax taxpayers send to Richmond for local transportation projects, though they acknowledge that that would be tough. Northern Virginia is long on tax revenue but short on votes in the General Assembly. Money collected in relatively wealthy Fairfax is directed to poorer parts of the state.

With Democratic and Republican strategists eager to capture the district, the campaigns have been furiously raising money. As of Sept. 30, Bulova had taken in $280,000 and Mason $259,000.

Mason cites his experience in government, his efforts as a transportation advocate and consultant, and a record of working across party lines. Having a Republican in the GOP-controlled General Assembly would benefit the district, he said, "hopefully in terms of committee assignments."

"My tag line is, 'Experience does matter.' Does is italicized. The point to be made is, having had the experience I've had . . . I'm ready to start on Day One. It's not a question of having OJT in Richmond -- on-the-job training," Mason said. "I understand the process, where the funding comes from. I understand the long-range plans" on transportation.

Bulova says he is energetic and open to new ideas, and he cites his role as co-chairman of a task force set up to help protect the Occoquan watershed. He says he is committed to representing the district "for the long haul."

"It's not a contest to see who has the longest resume. It's voting on who's going to be able to provide the best kind of leadership," Bulova said.

"My commitment is that if I can knock on 9,200 doors to get elected, you better believe that I'll take the time when I'm elected to make sure I'll get out into the community [and] get people better connected to their state government," Bulova said, adding that he would draw talented people from throughout the district into the process.

Two minor-party candidates are also seeking the seat.

Engineer Daniel Haugh, running as a member of the Independent Green Party, has called for a far-reaching, multibillion-dollar expansion of mass transit and rail statewide. "We're encouraging the rest of Virginia to see it our way in terms of mass transit by expanding our plans to encompass more of Virginia," Haugh said.

B. Scott McPherson, the Libertarian candidate, wants tax credits for families that school their children at home or send them to private schools. "My position is that school and state should be separated much like church and state," he said. "Government should get completely out of education."